From an Eight Chain Thru, Facing Lines, or other applicable formations.

Square Thru until the original Centers become Ends of Back-To-Back Lines and
until the original Outsides become Centers of Facing Lines; New Centers
(working in the middle) do the anything call or complete the
Square Thru n (continuing with alternating hands).

Notes:

The anything call or completing the Square Thru n
is done by the Centers only, working in the middle of the set
(Concentric).

If no n or if anything is given, assume n is
4. Most callers nearly always supply n or anything
so that there is no confusion.

Several callers, myself included, call this as Mixed Up Square
Thru, Centers go n More to clearly indicate the number of
additional hands for the new Centers.

From Eight Chain Thru:

beforeMixed Up Square Thru

after original Centers Square Thru 2 as original Ends Square Thru 1 and 1/4 In

afterCenters Left Square Thru 3

(done)

From Facing Lines:

beforeMixed Up Square Thru

after original Centers Square Thru 3 as original Ends Square Thru 2 and 1/4 In